Apparatus for detecting slidable member seizure and automatically disabling the same



Fe. N, 1969 o. WOOD 3,426,792

APPARATUS FOR DETECTING SLIDABLE MEMBER SEIZURE AND AUTOMATICALLY DISABLING THE SAME Sheet of 2 Filed Feb. 2. 1966 la' H 7 FIQST FHQ uvozAemc REST SERVO A REST VALVE BYPASS FLUID MEWS CONT VALVE soulzcE VALVE FHQST SPOOL JAM r2! DETEQT ACTUATOR 25 AND 43 SECOND LOAD SPOOL JAM -41 DETECTOR 31 33 -f-42 SECOND SECOND 34 g 3 sacouo 37 39 HVDIZAEFZIC W K 7 F'LUlD VALVE comeol. BWASS souace 32 MEANS VALVE VALVE 73 '7! selzvo 74 k 4 VALUE Q '7 /5 -T b I8 /53 1 F/RST sE/Pvo 1 8 (OWL mm 9 w 80 92 A "\TH 7 '1 6'5 a5 3 4 a1 SOLENOID P 89/ :9 l9\ l2 1 l l ACT:: 2 25 LOAD T'O SYSTEM H6 .3

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DEQGK h/o OD 'ATTOZ -EY5 Sheet i of2 E m EE E M EV/ w 5 1 H w E p illl j l w X MN a AA A 1 3 9s x mm 4 mm m m zmaomlu. WOP P5 0P D. WOOD APPARATUS FOR DETECTING SLIDABLE MEMBER SEIZURE AND AUTOMATICALLY DISABLING THE SAME Fern. 11. 1969.

Filed Feb. 2, 1966 5 A: N: i Q mh i g 5 v L A A 5 N:

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A TT'OPMEVS United States Patent 3,426,792 APPARATUS FOR DETECTING SLIDABLE MEMBER SEIZURE AND AUTOMATICALLY DISABLING THE SAME Derek Wood, Sun Valley, Calif., assignor to Bell Aerospace Corporation, a corporation of Delaware Filed Feb. 2, 1966, Ser. No. 524,435 US. Cl. 137-59612 Int. Cl. F15c 3/14; F16k 31/42, 37/00 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates generally to hydraeric systems which employ slidable members such as, for example,

control valves especially of the spool valve type, and

more particularly to apparatus for use in conjunction with such systems for detecting seizure of such members and providing an error signal in response thereto automatically effectively remove sucha seized member from the system.

The term hydraeric as used throughout this specification and the appended claims is defined as being generic to liquids and gases under pressure and includes generally both hydraulics and pneumatics.

It should be expressly understood that the present invention is adaptable for use in any application wherein it is desirable to detect unwanted relative movement between a slidable member and a reference point. For purposes of ease of description and clarity of illustration the present invention will be hereinafter specifically related to application as a control valve in a hydraeric system.

tion and description'is not to be taken as a limitation on p the scope of the presentinvention.

As is well known in the prior art it is common to use slida'ble control valves, particularly those normally referred to as spool valves, for the control of hydraeric fluid to in turn position a desired apparatus in response to the application of command or control signals. It is also known in the prior art that under certain malfunction circumstances the control valve will adhere or seize to the walls of the cylinder within which it is slidably disposed. Such a malfunction of the control valve is commonly referred to as a spooljam or a spool seizure. When such a spool jam or spool seizure occurs, the command signals applied to the system are not responded to by the control valve and as a result thereof the apparatus which is controlled will not move its position to that which is desired and commanded by the'command signals, that is, the flow of hydraeric fluid to the load is inconsistent with the command signals. Depending upon the particular apparatus being controlled, such failure to respond to the command signals can in the worst case destroy completely the apparatus which is being controlled.

Where the conditions are critical, i.e., where a failure to respond to a command signal in the manner above referred to would cause a destruction of the controlled apparatus, it obviously becomes necessary to detect such malfunctions as spool seizures and take immediate action with respect thereto to prevent destruction of the controlled apparatus and thereby a complete mission failure.

3,426,792 Patented Feb. 11, 1969 In simple situations where speed of response is not a critical factor, one can obviously provide an error indicating signal to an operator and permit the operator to act in accordance with the error signal applied to deactivate the system. However, where speed becomes a critical factor, the time required for the operator to detect the occurrence of an error signal to interpret the same and to decide and then act requires more time that is required for the apparatus to destroy itself. Thus it can be seen that reliance upon an operator under these circumstances is not feasible.

Accordingly, it is an object of the present invention to provide an apparatus for detecting failure of a control valve in a hydraeric control system to respond to command signals applied thereto.

It is another object of the present invention to provide apparatus for detecting the failure of a control valve in a hydraeric control system to respond to command signals applied thereto an automatically to disable that control valve which has failed to respond from further system control.

It is another object of the present invention to provide apparatus for detecting failure of a control valve in a hydraeric control system which removes system pressure automatically from that portion of the apparatus wherein the control valve failed to respond without affecting application of the system pressure to any other desired part of the system.

It is a further object of the present invention to provide such apparatus for detecting a spool seizure and automatically disabling the failed spool valve which is simple, rugged, and reliable even under adverse operating conditions.

Other objects and advantages of the present invention both as to its organization and method of operation will become apparent from a consideration of the following description taken in conjunction with the accompanying drawings which are presented by way of example only and are not intended as a limitation upon the scope of the present invention and in which:

FIGURE 1 is a schematic representation, in block It is to be further understood that such specific illustra- .1 form, of an apparatus embodied in hydraeric control system in accordance with the present invention;

FIGURE 2 is a schematic representation, partly in cross-sectoin and partly in block form, of a valve means and its interrelation with the spool jam detector in accordance with the present invention;

FIGURE 3 is a schematic representation, partly in cross-section and partly in block form, of a bypass valve which may be used in a system in accordance with the present invention;

FIGURE 4 is a schematic representation, partly in cross-section, illustrating the spool jam detector apparatus in generalized form; and

FIGURE 5 is a fragmentary schematic representat on, partly in cross-section, of a portion of the structure illustrated in FIGURE 4 and representing in more detail one specific embodiment of a spool jam detection apparatus in accordance with the present invention.

Apparatus for detecting spool valve seizures and automatically eliminating the effects thereof in accordance with the 'present invention includes a valve means which connects a source of hydraeric fluid to the system and which valve means is normally open during operation of the system. A detector-means is afiixed to the control valve within the system and is adapted to detect non-remanner as to disable the seized control valve from further control of the system.

Referring nOW to the drawings and more particularly to FIGURE 1 thereof, there is illustrated a hydraeric control system embodying apparatus in accordance with the present invention. As is shown, the illustration is in block schematic form and includes a first hydraeric fluid source 11 which, as above referred to, may be hydraulic or pneumatic fluid under pressure and which is connected by way of conduit 12 to a first valve means 13. The opening or closing of the first valve means 13 controls the application of the hydraeric fluid from the source thereof to the remaining portion of the system. A conduit 14 interconnects the first valve means 13 to a first servo control valve 15. An additional conduit means 16 is connected to the conduit means 14 and connects thereby the output of the first valve means to a first bypass valve 17. The output of the first servo control valve 15 is applied by way of a conduit means 18 through the first bypass valve 17 to an output conduit 19. As will become more apparent hereinbelow, the position of the first bypass valve 17 determines whether or not the hydraeric fluid passing through the firs-t servo control valve 15 has any effect upon the actuator and load 25. A first spool jam detector 21 is interconnected by means as shown at 22 to the first servo control valve 15 and functions to generate a signal indicative of a valve spool jam or seizure. The signal so generated is connected by means of lead or conduit 23 to the first valve means 13.

Also included within the system is a second hydraeric fluid source 31 which is connected by means of conduit 32 to a second valve means 33. The output of the second valve means 33 is connected by means of conduit 34 to a second servo control valve 35. A conduit 36 is also connected to the conduit 34 and thereby connects the output of the second valve means 33 to a second bypass valve 37. The output of the second servo control valve is also connected by conduit means 38 through the second bypass valve 37 to an output conduit 39. The output conduits 19 and 39 are connected to the actuator and load 25. Also connected to the second servo control valve 35 by the connection means 42 is second spool jam detector 41. The output signal generated in response to any valve spool seizure (spool jam) is connected by means of lead or conduit 43 to the second valve means 33.

In operation under normal conditions, i.e. when there is no spool valve seizure, the first and second valve means is each open and thus applies the first and second hydraeric fluids from their respective sources to the remainder of the system. Also the first and second bypass valves are normally closed thus causing the output of each of the first and second servo valves to be applied through the bypass valves and to the actuator and load 25. In the event of a valve spool seizure, for example in the first servo control valve 15, a signal is generated by the first spool jam detector 21 and is applied to the first valve means 13 causing the same to close. Upon closure of the first valve means 13 hydraeric fluid pressure from the source 11 is removed from the system. Under these conditions, the first bypass valve 17 is permitted to open thus disabling the first servo control valve 15 from the control of the actuator and load 25. As should be apparent, in the event that the first servo control valve 15 is thusly disabled, the second servo control valve 35 continues to operate in its normal manner to control the position of the load through the actuator and would continue to so function unless a spool valve seizure occurred in the second control valve 35.

Referring now to FIGURE 2, there is therein schematically illustrated a valve means which may be utilized for the first and second valve means 13 and 33 respectively. It should, however, be understood that the valve means illustrated in FIGURE 2 is merely illustrative and it should be understood any valve means capable of performing the desired function may be utilized. As is shown, the valve means 13 includes a housing 50 defining a first chamber 51 and a second chamber 52 which are interconnected by a bore 53. The system hydraeric fluid pressure source designated P and also by the numeral 1 1 is connected by means of the conduit 12 to the chamber 51. System return, designated R, and also by the numeral 54 is connected by means of conduit 55 to a port 56 which communicates with the chamber '52. Also communicating with the chamber 52 is a port 57 to which is connected a conduit means 58 which in turn is connected to the various portions of the system as is illustrated and indicated by the legend associated therewith.

A port 61 also communicates with the bore 53 and has a conduit 62 connected thereto. The conduit 62 also is connected throughout the system and carries system fluid from the source 11 thereof to conduits 14 and 16, as well as throughout the remainder of the system, as will become more readily apparent hereinbelow.

A first ball 63 is disposed within the chamber 51 and a second ball 64 is disposed within the chamber 52. A rod 65 interconnects the two balls 63 and 64. An actuating rod 66 is interconnected between the ball 64 and a solenoid 67. A resiliently deformable means such as a spring 68 is disposed within the chamber 51 between the ball 63 and the end wall 69 of the housing 50. During the period of time that the solenoid is non-energized, as is illustrated in FIGURE 2 embodiment of the valve 13, the spring 68 forces the ball 63 into the position illustrated in FIGURE 2 thereby precluding system fluid from the source 11 from entering a conduit 62. As is also illustrated during this period of time, the conduit 62, i.e. system pressure, is connected to system return 54 through port 61, bore 53 and port 56.

In order to actuate the solenoid 67 there is provided a source of potential such as the battery 71 which has one terminal 72 connected to ground as illustrated. The other terminal 73 passes through a switch 74, shown in the non-operated position, and which may for example be the operators manual switch, which, when actuated, places the system in condition for operation. The switch in turn is connected to the spool jam detector 21 which in turn is connected to the solenoid 67. Upon closing of the switch 74 electrical potential is applied through the spool jam detector 21 to the solenoid 67 thereby energizing the same and causing the balls 63 and 64 to move to the right.

Upon movement of the balls 63 and 64 toward the right as viewed in FIGURE 2, the bore 53 is opened to system fluid from the source 11 thereof and simultaneously the bore 53 is closed by the ball 64 from communication with system return 54. Therefore, system fluid is applied to the hydraeric control system through the conduit 62 and the system is also connected, wherein such is desired, for normal operational purposes, to system return 54 through the conduit 58.

So long as the system operates in a normal fashion, the valve means remain open as above described. However, in the event of a spool valve seizure the spool jam detector 21 generates an error signal which removes the electrical energy from source 71 thereof from the solenoid 67 causing it to thereby be de-energized. Upon the de-energization of the solenoid 67, the balls 63 and 64 are returned toward the left as viewed in FIGURE 2 by the spring 68 thus placing the valve means 13 again into the position as shown in FIGURE 2, thereby removing system fluid from the valve spool which has seized. This particular operation and the manner in which the signal is generated will be more fully described hereinafter.

Referring now to FIGURE 3, there is schematically illustrated a bypass valve showing its operation in conjunction with apparatus in accordance with the present invention. As is shown in FIGURE 3 a servo valve 15 is interconnected by the conduit 18 through the bypass valve 17 to the actuator and load 25 by means of the output conduits 19. The bypass valve during normal operation occupies the position as illustrated in FIGURE 3. In this position, system pressure is applied through the conduit 16 from the source P thereof to a chamber 81 pro vided at the left end of a bore 82 provided in the housing 80. Under these conditions the spool consisting of the lands 83 and 84 interconnected by the rod 85 occupies the position illustrated in FIGURE 3 and in so doing compresses the resiliently deformable means such as the spring 86, positioned in the chamber 87. In the position illustrated in FIGURE 3, the land 83 blocks the ports 88 and 89 thus causing fluid to flow from the servo valve 15 through the left conduit 18, to the annulus 91, through the left conduit 19, and to the actuator and load 25. Fluid also flows from the servo valve 15, through the right conduit 18, through the port 92, into the bore 82 between the lands, through the port 93 and through the right conduit 19 to the actuator and load 25. Thus in normal operation the servo valve 15 may control the position of the actuator and load 25.

In the event of a seizure of the valve spool, such that the spool jam detector actuates as was described in conjunction With FIGURE 2 above, causing the first valve means 13 to become closed, i.e. occupy the position illustrated in FIGURE 2, the pressure is removed from the chamber 81 in the housing 80 thus causing the spring 86 to move the spool toward the left and against the side wall 94 of the housing 80. In this position ports 88 and 89 are in communication with the bore 82 between the lands 83 and 84 as are ports 92 and 93. Thus any hydraeric fluid in the conduits 19 and the conduits 18 is bypassed by finding direct communication through the bore 82 in the manner of a short circuit, thus rendering the servo valve 15 ineflective to control the position of the actuator. Obviously other bypass valves may be utilized to perform this function should such be deemed desirable in any given instance.

Referring now more particularly to FIGURE 4, there is illustrated first and second servo valves 15 and 35 respectively adapted to control the flow of hydraeric fluid to an actuator and load (not shown in FIGURE 4) in response to application of command signals applied thereto, and further adapted in such a manner that in the event of a seizure of a control valve within the servo valve an error signal is developed.

As is illustrated in FIGURE 4, the servo valve includes the typical torque motor 101 responsive to electrical signals applied to the terminals 102 to operate a pilot valve such as to cause a change in position of a flapper 103 to vary the pressure at the nozzles 104, all of which is old and well-known in the prior art and further discussion thereof is not deemed necessary at this point. For a further and more detailed description, if such is desired, reference is made to US. Patents 2,947,285 and 2,947,286. The variation in pressure of the nozzles 104 is applied through the conduits 105 and 106 to opposite ends of the control valve. A similar structure is shown at 111 to that above described with respect to the torque motor, flapper and nozzles which operates in the same fashion to provide a variance in pressure in conduits 112 and 113 which is applied to opposite ends of the control valve. It should thus be recognized that the control valve is operable in response to the changes in pressure appearing at the output of each of the pilot valves individually. As is illustrated in FIGURE 4, each of the pilot valves are operating simultaneously and applying hydraeric pressure signals to opposite .ends of the control valve simultaneously, i.e., in parallel, and are each therefore controlling the positioning of the control valve.

The control valve as illustrated in FIGURE 4, includes a drive spool 121 and a valve spool 122. The valve spool 122 is positioned between the lands 123 and 124 of the drive spool 121 by means of a resiliently deformable means such as drive springs 125 and 126 respectively. The valve spool 122 operates as a four-way valve to control the flow of fluid from the source P to the actuator and from it to the return R as is well known in the prior art. With respect to the second servo valve 35, a valve spool 132 is positioned by drive springs 133 and 134 between lands 124 and 135 respectively of the drive spool 121. The valve spool 132 operates in a manner well known to the art as a four-way valve to control the flow of hydraeric fluid from the source P thereof to the actuator and from it to the system return R It should now be recognized that during normal operation of the apparatus illustrated in FIGURE 4, dilferential pressure is applied across the drive spool 121 to cause it to translate in accordance therewith. As the drive spool 121 translates in response to the application of the differential pressure thereacross, the valve spools 122 and 132 travel therewith as force is applied through the respective drive springs at opposite ends of the valve spools, causing them to move and thus track the movements of the drive spool 121. It should be noted, however, that each of the valve spools is provided with a bore, for example at 127 with respect to the spool 122 and at 137 with respect to the spool 132, and as a result thereof the drive spool 122 and the valve spools 122 and 132 are adapted for relative movement.

As a result of the arrangement of the valve spools 122 and 132 so that they are movable relative to the drive spool 121 it can thus be seen that in the event either of the valve spools 122 and 132 seizes to the cylinder within which it is disposed and thereby refuses to obey the command signals applied through the pilot valve, the drive springs for example 125 and 126 expand or contract thus causing the drive spool to continue movement. Under these conditions the valve spool which is not seized to the walls of its cylinder continues to translate and thereby controls the actuator as above described. In the event however of a seizure of the valve spool, for example valve spool 122, and for purposes of description assume that the drive spool is attempting to move toward the left as viewed in FIGURE 4, then spring 126 contracts and spring 125 expands.

Under these conditions apparatus is afiixed to the drive and valve spools to detect such contraction or expansion of the drive springs supporting the valve spools 122 and 123 as above described. Such apparatus for example may be detector means illustrated at 141 and affixed to the valve spool 122 having a counterpart 142 aflixed to the land 124 of the drive spool. Similar apparatus is as illustrated at 143 affixed to the valve spool 132 and at 144 to the land 124 of the drive spool 121.

Thus utilizing the example above referred to where the spring 126 contracts, the apparatus at 141 and 142 detects such contraction of the spring 126 since the elements 141 and 142 now move closer together than they normally should be and thereby generate a signal. Conversely, should the drive spool 121 be moving toward the right while the valve spool 122 is seized, the elements 141 and 142 move farther apart than they normally should and thereby generate an output signal. Thus it can be seen that the deflection of the drive springs 125 and 126 is measured by the elements 141 and 142 and may be set to provide an error signal in the event the measured deflection exceeds a predetermined amount. The elements 143 and 144 operate in a similar manner.

Mechanization of the elements 141, 142, 143 and 144 into a particular device for providing a specific output signal is illustrated in FIGURE 5 to which reference is hereby made. As is illustrated in FIGURE 5 the valve spool 122 has an actuator arm 151 aflixed rigidly thereto. The actuator arm 151 has an extension finger 152 disposed downwardly between a pair of microswitches 153 and 154. Each of the microswitches is in turn mounted upon a movable flange which is rigidly affixed to the land 124 of the drive spool 121. It can thus be seen that under normal operating conditions the finger 121 remains disposed between but not in contact with the microswitches 153 and 154 and the entire apparatus translates within the chamber 156 provided within the wall of the housing 57. If, however, the drive spring 1.26 deflects, for example in compression, by a predetermined amount the finger 152, actuates the microswitch 154. On the other hand should the spring deflect in the opposite direction, that is expansion, then the finger 152 actuates the microswitch 153. A similar operation occurs with respect to the two microswitches on the right hand side of the cavity or chamber 156 which are operable by the arm and finger aflixed to the valve spool 132 as illustrated.

Referring now again to FIGURE 2 it can be seen that the microswitches 153 and 154 would be included within the spool jam detector 121. In the event of the actuation of either microswitch the circuit supplying electrical energy to the solenoid 67 is opened thus causing the solenoid to de-energize with the resultant actuation of the bypass valve as above referred to.

There has thus been disclosed an apparatus which is particularly adapted for utilization with a hydraeric control system and which is capable of detecting valve spool seizures or jams and producing an error signal which automatically disables that valve spool which has seized from further control of the device which is being positioned by this system. Although a specific illustration of an apparatus constructed in accordance with the present invention has been illustrated and above described, such detailed illustration and description is to be taken by way of an illustrative example only and is not intended as a means of limiting the claims appended hereto.

What is claimed is: 1. In a hydraeric system having a member slidable in response to signals applied to said system, apparatus for detecting seizure of said member and effectively eliminating the affects thereof, said apparatus comprising:

a source of hydraeric fluid; valve means connecting said source to said system and being normally open during operation of said system thereby to apply hydraeric fluid to said system;

detector means aflixed to said member for detecting nonresponse of said member to applied signals and adapted to generate an error signal in response thereto;

and means connecting said error signal to said system to disable said member thereby to eliminate the etfects thereof.

2. Apparatus as defined in claim 1 wherein said valve means is a solenoid actuated valve and said error signal generated by said detector means is connected to said solenoid to cause said solenoid to close said valve and remove said fluid source from said system.

3. Apparatus as defined in claim 1 in which said member includes a drive spool and a follower spool, means mounting said drive spool movable relative to said follower spool, said detector means being operable to generate said error signal in response to said relative movement.

4. Apparatus as defined in claim 3 in which said mounting means includes spring means disposed between said drive spool and said follower spool at each end of said follower spool thereby to permit bi-directional relative movement between said spools.

'5. Apparatus as defined in claim 4 in which said detector means includes switch means mounted on one of said spools and switch actuating means mounted on the other of said spools, said switch actuating means causing actuation of said switch means and generation of said error signal upon relative movement between said spools.

6. Apparatus as defined in claim 5 wherein said valve means is a solenoid actuated valve and said switch means upon actuation thereof causes said solenoid to close said valve means thereby removing said source of hydraeric fluid from said system.

7. Apparatus as defined in claim 6 in which said member is a control valve means and said follower spool is a valve spool controlling hydraeric flow and which includes a bypass valve connected to the output of said control valve and operable in response to removal of said hydraeric fluid from said system to connect the output passageways from said control valve together.

References Cited UNITED STATES PATENTS 3,253,613 5/1966 Richolt 137596 M. CARY NELSON, Primary Examiner.

R. J. MILLER, Assistant Examiner.

US. Cl. X.R. 

